Method of lubricating refractory wires during drawing the same.



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L FALRKAS, 0F PROVIDENCE, RHODE ISLAND, ASSIGNOR- 0F ONE-HALF T0 ARTHUR B. LISLE, OF PROVIDENCE, RHODE ISLAND.

METHOD OF LUBRICATING REFRACTORY WIRES DURING DRAWING THE SAME.

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To all whom'z'zf may concern:

Be it known that I, KARL FARKAs, a citizen of the Kingdom of Hungary, and a resident of Providence county of Providence, State of Rhode Island, have invented certain new and useful Improvements in Methods of Lubricating Refractory W'ires During Drawing the Same, of which the following is a specification.

This invention has reference to a novel process of lubricating refractory wires during drawing the same out into finer wire. It pertains particularly to a novel process of lubricating refractory wires, such as molybdenum. tantalum and especially tungsten wire when the same is drawn out to such a fineness as required for use in metallic filament lamps.

Heretofore in the art of drawing tungsten wires for use in metallic filament lamps graphite powder has been used as a lubricant. The graphite powder was suspended in water or oil and acted as a lubricant when the wire passed the diamond die. A great pressure is exerted upon the wire while passing the diamond die and the graphite powder is mechanically forcedinto the surface of the wire where it remains. When such wire charged with more or less of graphite in its surface portion is electrically heated during the manufacture of metallic filament lamps the formation of carbid is evident and a really pure illuminant for a metallic lamp can not be obtained in this way.

In order to produce tungsten wire for metallic filament lamps and especially fine wire for tungsten lamps of limited candle power I have devised a novel method for lubricating the tungsten wire while passing the diamond die. I have found that graphite powder especially the artificial graphite powder which latter is hard even when transformed into impalpable powder ofiers sufficient resistance to be forced into the surface of the wire while passing the diamond die. For this reason I employ a substance which has a low specific gravity and accordingly is exceedingly light but capable of being mixed with water or oil. Furthermore the novel substance is not a chemical element like graphite but a metallic oxid. Various light metallic oXids may be used for this purpose, but I prefer to use the exceedingly light, white magnesium oxid,

Specification of Letters Patent.

Patented-Jan. f5, il ild.

MgO, or as it is commonly called magnesia. This substance represents a white tasteless powder of feeble alkaline reaction and has a specific gravity of somewhat above 3.

-Magnesium oxid or magnesia is practically insoluble in water and scarcely fuses at the temperature of the oxyhydrogen flame. This property of the magnesia renders it espe' cially valuable for the purpose of lubricating tungsten wire during drawing the same because it does not fuse by the relatively high heat produced when the wire passes the diamond die, especially when the wire is heated or even electrically heated before it passes the heated die. It is well known that the light fiocky magnesium oxid becomes somewhat denser when heated but all kinds of magnesia may be used as a lubricant in the method of drawing fine tungsten wire.

The magnesia is preferably mixed with Water to form an aqueous paste of such consistency as to adhere to the wire when passed through such paste. The slight alkaline magnesia tends to clean the wire mechanically while in contact therewith. The magnesia paste becomes dry during the process ofdrawing fine wire and is easily removed from the drawn fine wire by simply washing it with distilled water and wiping it. The magnesia in contact with the wire in form of an aqueous paste becomes dry on the heated wire and is completely dry after having passed the usually heated diamond die. For this reason the removal of the traces of magnesia which may adhere to the fine finished wire is easily effected by washing and wiping.

In carrying the invention into practice ll simply prepare with distilled water a paste of magnesia of proper consistency and pass the wire through the same. The aqueous magnesia paste sticks to the wire and acts as a lubricator. The wire then is heated,

preferably by an electric current and passed 100 through the diamond die which also is heated, usually to a cherry red. This operation is repeated until the desired fineness of tungsten wire has been obtained. The

light lubricant consisting of magnesium oxid 105 No im- 11d purities which may form. compounds with the metal are forced into the surface of the wlre during the process of drawing out the same by using magnesium oxid as a lubricant.

I claim as my invention? 1. The method of lubricating wires of refractory metals while drawing the same'out into finer wire consisting in applying a paste of an infusible light metallic oxid to the wire, and then passing the same through a diamond die.

2. The method of lubricating wires of refractory metals While drawing the same out into finer wire consisting in applying an aqueous paste of light metallic oxid to the surface of the wire, and then passing the same through a diamond die.

3. The method of lubricating tungsten wire while drawing out the same into finer wire consisting in applying an aqueous paste of a light metallic oxid to the surface of the wire, and then diamond die.

passing the same through a 4. The method of lubricating tungsten wire while drawing out the same intofiner wire consisting in applying an aqueous paste of magnesium oxid to its surface, and then passing the .Wire through a diamond die.

5. The method of lubricating tungsten wire While drawing out the same into finer wire consisting in applying. an'aqueous paste of magnesium oxid to its surface, then heating the wire, and passing the lubricated, heated wire, through a diamond die.

v6. The method of lubricating tungsten wire while drawing out the same into finer wire consisting in applying an aqueous paste of magnesium oxid toits surface, then heating the wire, and then passing the lubricated heated wirethrough a heated diamond die.

Signed at New York, N. Y., this 27th day of April 1916.

KARL FARKAS. Witnesses:

LILLEY E. SCHMIDT, SOPHIE Gnm. 

